You can control the plumber who is not performing and causing delays by hiring a different contractor.  

I would use a reputable real estate attorney.

Looking for a reputable/insured contractor to add bedroom and bathroom in my basement.

I'm currently looking for a new plumber in the Albany area and was wondering if anyone had any recommendations. 

Obviously looking to have a professional plumber do it for me.

Get a basic title search from a reputable title insurance company.

Depending on the contract that you sign with your renters may be you need to fix or replace the appliances, you need to fix water leaks, you need to call a plumber, and electrician and this problems sometimes are expensive to fix.

They want to grow into a $200 million company a year and have a great reputation locally for decades.

They recommended having a plumber check out the issue. 

A house is a house; they are fairly simple things; and any reputable tradesman should be in and out in 1-3 days unless you're doing a 100% gut to the studs and re-plumbing/rewiring the entire house.